二项堆

//二项堆的介绍参考<<数据结构>>Ellis Horowitz等著，李建中等译（c语言版）P289
/*
* 2008/07/08 By YaoJianming
* */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct element {
        int key;
};
struct bheap {
        element data;
        bheap *child;
        bheap *left_link;
        bheap *right_link;
        int degree;
};
#define TREELEN 8
void join_min_trees(bheap *&a, bheap *b)
{
        if(a->data.key < b->data.key) {
                if(a->child == NULL) {
                        a->right_link = a->left_link = a;
                        b->right_link = b->left_link = b;
                } else {
                        bheap *temp = a->child->left_link;
                        a->child->left_link = b;
                        b->right_link = a->child;
                        b->left_link = temp;
                        temp->right_link = b;
                }
                a->child = b;
                a->degree++;
        } else {
                if(b->child == NULL) {
                        a->right_link = a->left_link = a;
                        b->right_link = b->left_link = b;
                } else {
                        bheap *temp = b->child->left_link;
                        b->child->left_link = a;
                        a->right_link = b->child;
                        a->left_link = temp;
                        temp->right_link = a;
                }
                b->child = a;
                b->degree++;
                a = b;
        }
}
element del(bheap *&a)
{
        element temp = a->data;
        bheap *tree[TREELEN];
        for(int i=0; i<TREELEN; ++i) {
                tree[i] = NULL;
        }
        bheap *p1, *p2;
        if(a->left_link != a) {
                p1 = a->left_link;
                p1->right_link = a->right_link;
                a->right_link->left_link = p1;
        }
        p2 = a->child;
        bheap *m1 = p1;
        bheap *m2 = p2;
        do {
                if(m1 == NULL) break;
//              printf("%d\n", m1->data.key);
                int degree;
                bheap *w = m1->right_link;
                for(degree=m1->degree; tree[degree]; ++degree) {
                        join_min_trees(m1, tree[degree]);
                        tree[degree] = NULL;
                }
                tree[degree] = m1;
                m1 = w;
        } while (m1 != p1);
        do {
                if(m2 == NULL) break;
//              printf("%d\n", m2->data.key);
                int degree;
                bheap *w = m2->right_link;
                for(degree=m2->degree; tree[degree]; ++degree) {
                        join_min_trees(m2, tree[degree]);
                        tree[degree] = NULL;
                }
                tree[degree] = m2;
                m2 = w;
        } while (m2 != p2);
        int k = 0;
        for(int i=0; i<TREELEN; ++i) {
                if(tree[i] == NULL) continue;
                k++;
                if(k == 1) {
                        tree[i]->right_link = tree[i]->left_link = tree[i];
                        a = tree[i];
                } else if(k > 1) {
                        bheap *temp = a->right_link;
                        a->right_link = tree[i];
                        temp->left_link = tree[i];
                        tree[i]->right_link = temp;
                        tree[i]->left_link = a;
                        if(a->data.key > tree[i]->data.key) a = tree[i];
                }
        }
        return temp;
}
void insert(bheap *&a, bheap *b)
{
        if(a == NULL) {
                a = b;
                return;
        }
        bheap *temp = a->right_link;
        a->right_link = b;
        b->right_link = temp;
        temp->left_link = b;
        b->left_link = a;
        if(a->data.key > b->data.key) {
                a = b;
        }
}
void merge(bheap *&a, bheap *b)
{
        if(a == NULL) {
                a = b;
                return;
        }
        bheap *p1 = a->right_link;
        bheap *p2 = b->left_link;
        a->right_link = b;
        b->left_link = a;
        p1->left_link = p2;
        p2->right_link = p1;
        if(a->data.key > b->data.key) {
                a = b;
        }
}
void traverse(bheap *a)
{
        bheap *p = a;
        do {
                printf("%d %d\n", p->data.key, p->degree);
                if (p->child != NULL) {
                        traverse(p->child);
                }
                p = p->right_link;
        } while(p != a);
}
int main()
{
        bheap *a = NULL;
        for(int i=1; i<=8; ++i) {
                bheap *p = new bheap;
                p->right_link = p->left_link = p;
                p->child = NULL;
                p->data.key = i;
                p->degree = 0;
                insert(a, p);
        }
        bheap *b = NULL;
        for(int i=9; i<=17; ++i) {
                bheap *p = new bheap;
                p->right_link = p->left_link = p;
                p->child = NULL;
                p->data.key = i;
                p->degree = 0;
                insert(b, p);
        }
        del(a);
        del(b);
        merge(a, b);
        traverse(a);
}